Fabricating die with separate test pads selectively coupled to cores

Abstract

Timely testing of die on wafer reduces the cost to manufacture ICs. This disclosure describes a die test structure and process to reduce test time by adding test pads on the top surface of the die. The added test pads allow a tester to probe and test more circuits within the die simultaneously. Also, the added test pads contribute to a reduction in the amount of test wiring overhead traditionally required to access and test circuits within a die, thus reducing die size.

1. A process of fabricating die comprising:
 A. processing at least one die on a semiconductor wafer, the processing including embedding circuit cores in the die, with each core having input leads and output leads; 
 B. providing functional pads at the periphery of the die that are coupled to the input leads and output leads of the circuit cores for communicating functional signals to and from the circuit cores; 
 C. providing test pads on the top surface of the die that are separate from the functional pads and are selectively coupled to the input leads and the output leads of the circuit cores for communicating test signals to and from the circuit cores; and 
 D. forming test circuits in the die that selectively couple the test pads to the input leads and output leads. 
 
   
   
     2. The process of  claim 1  including coupling input leads and output leads adjacent the periphery of the die to the functional pads. 
   
   
     3. The process of  claim 1  including coupling input leads and output leads that are not adjacent the periphery of the die to the functional pads. 
   
   
     4. The process of  claim 1  including connecting the input leads and output leads of a circuit core to the input leads and output leads of another circuit core. 
   
   
     5. The process of  claim 1  including maintaining the input leads and output leads of a circuit core that are connected to the input leads and output leads of another circuit core separate from the functional pads.